Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective Tax Rate
Income/(Loss) before income taxes	$ 103	$ (138)	$ (71)	$ (173)
Income tax expense/(benefit)	$ 4	$ 25	$ (1)	$ 47
Effective tax rate	3.90%	(18.10%)	1.40%	(27.20%)
Statutory tax rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 39		$ 39
Unrecognized tax benefits, penalties and interest accrued	$ 4		$ 4